John Lawrence Cardy FRS (born 19 March 1947, England) is a

British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories and Crown Dependencies. * British national identity, the characteristics of British people and culture ...

– American

theoretical A theory is a systematic and rational form of abstract thinking about a phenomenon, or the conclusions derived from such thinking. It involves contemplative and logical reasoning, often supported by processes such as observation, experimentation, ...

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...

. He is best known for his work in theoretical

condensed matter physics Condensed matter physics is the field of physics that deals with the macroscopic and microscopic physical properties of matter, especially the solid and liquid State of matter, phases, that arise from electromagnetic forces between atoms and elec ...

and

statistical mechanics In physics, statistical mechanics is a mathematical framework that applies statistical methods and probability theory to large assemblies of microscopic entities. Sometimes called statistical physics or statistical thermodynamics, its applicati ...

, and in particular for research on

critical phenomena In physics, critical phenomena is the collective name associated with the physics of critical points. Most of them stem from the divergence of the correlation length, but also the dynamics slows down. Critical phenomena include scaling relations ...

and

two-dimensional conformal field theory A two-dimensional conformal field theory is a quantum field theory on a Euclidean two-dimensional space, that is invariant under local conformal transformations. In contrast to other types of conformal field theories, two-dimensional conformal fi ...

. He was an undergraduate and postgraduate student (now an

Honorary Fellow Honorary titles (professor, president, reader, lecturer) in academia may be conferred on persons in recognition of contributions by a non-employee or by an employee beyond regular duties. This practice primarily exists in the UK and Germany, as ...

) at

Downing College, Cambridge Downing College is a constituent college of the University of Cambridge and currently has around 950 students. Founded in 1800, it was the only college to be added to the university between 1596 and 1869, and is often described as the oldest of ...

, before moving to the

University of California, Santa Barbara The University of California, Santa Barbara (UC Santa Barbara or UCSB) is a Public university, public Land-grant university, land-grant research university in Santa Barbara County, California, United States. Tracing its roots back to 1891 as an ...

, where he joined the faculty in 1977. In 1993, he moved to the

University of Oxford The University of Oxford is a collegiate university, collegiate research university in Oxford, England. There is evidence of teaching as early as 1096, making it the oldest university in the English-speaking world and the List of oldest un ...

, where until 2014 he was a

Fellow A fellow is a title and form of address for distinguished, learned, or skilled individuals in academia, medicine, research, and industry. The exact meaning of the term differs in each field. In learned society, learned or professional society, p ...

All Souls College All Souls College (official name: The College of All Souls of the Faithful Departed, of Oxford) is a constituent college of the University of Oxford in England. Unique to All Souls, all of its members automatically become fellows (i.e., full me ...

(now

Emeritus ''Emeritus/Emerita'' () is an honorary title granted to someone who retires from a position of distinction, most commonly an academic faculty position, but is allowed to continue using the previous title, as in "professor emeritus". In some c ...

) and a

Professor Professor (commonly abbreviated as Prof.) is an Academy, academic rank at university, universities and other tertiary education, post-secondary education and research institutions in most countries. Literally, ''professor'' derives from Latin ...

Physics Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...

in the

Rudolf Peierls Sir Rudolf Ernst Peierls, (; ; 5 June 1907 – 19 September 1995) was a German-born British physicist who played a major role in Tube Alloys, Britain's nuclear weapon programme, as well as the subsequent Manhattan Project, the combined Allied ...

Centre for Theoretical Physics. He was a Visiting Professor and then a Research Physicist (2015–2023) at the

University of California, Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California), is a Public university, public Land-grant university, land-grant research university in Berkeley, California, United States. Founded in 1868 and named after t ...

. His research prior to 1978 was in

particle physics Particle physics or high-energy physics is the study of Elementary particle, fundamental particles and fundamental interaction, forces that constitute matter and radiation. The field also studies combinations of elementary particles up to the s ...

, in particular high energy

scattering theory In physics, scattering is a wide range of physical processes where moving particles or radiation of some form, such as light or sound, are forced to deviate from a straight trajectory by localized non-uniformities (including particles and radiat ...

. After this, he applied methods of

quantum field theory In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines Field theory (physics), field theory and the principle of relativity with ideas behind quantum mechanics. QFT is used in particle physics to construct phy ...

and the

renormalization group In theoretical physics, the renormalization group (RG) is a formal apparatus that allows systematic investigation of the changes of a physical system as viewed at different scales. In particle physics, it reflects the changes in the underlying p ...

condensed matter Condensed matter physics is the field of physics that deals with the macroscopic and microscopic physical properties of matter, especially the solid and liquid phases, that arise from electromagnetic forces between atoms and electrons. More gen ...

, especially to

in both pure and disordered equilibrium and non-equilibrium systems. In the 1980s he helped develop the theory of

conformal invariance Conformal may refer to: * Conformal (software), in ASIC Software * Conformal coating in electronics * Conformal cooling channel, in injection or blow moulding * Conformal field theory in physics, such as: ** Boundary conformal field theory ** C ...

and its applications to these problems, ideas which also had an impact in

string theory In physics, string theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings. String theory describes how these strings propagate through space and intera ...

and the physics of

black holes A black hole is a massive, compact astronomical object so dense that its gravity prevents anything from escaping, even light. Albert Einstein's theory of general relativity predicts that a sufficiently compact mass will form a black hole. Th ...

. In the 1990s he used conformal invariance to derive many exact results in

percolation In physics, chemistry, and materials science, percolation () refers to the movement and filtration, filtering of fluids through porous materials. It is described by Darcy's law. Broader applications have since been developed that cover connecti ...

and related probabilistic problems. This helped inspire the work of mathematicians which was recognised by the award of the

Fields Medal The Fields Medal is a prize awarded to two, three, or four mathematicians under 40 years of age at the International Congress of Mathematicians, International Congress of the International Mathematical Union (IMU), a meeting that takes place e ...

Wendelin Werner Wendelin Werner (born 23 September 1968) is a German-born French mathematician working on random processes such as self-avoiding random walks, Brownian motion, Schramm–Loewner evolution, and related theories in probability theory and mathematic ...

in 2006, and to Stanislav Smirnov in 2010. More recently he has worked on questions of

quantum entanglement Quantum entanglement is the phenomenon where the quantum state of each Subatomic particle, particle in a group cannot be described independently of the state of the others, even when the particles are separated by a large distance. The topic o ...

and

non-equilibrium Non-equilibrium may refer to: * generally the absence of an equilibrium * Non-equilibrium economics * Non-equilibrium statistical mechanics * Non-equilibrium thermodynamics {{disambiguation ...

dynamics in many-body systems, and on non-local field theory. He was elected as a

Fellow of the Royal Society Fellowship of the Royal Society (FRS, ForMemRS and HonFRS) is an award granted by the Fellows of the Royal Society of London to individuals who have made a "substantial contribution to the improvement of natural science, natural knowledge, incl ...

in 1991, received the

Dirac Medal The Dirac Medal or Dirac prize can refer to different awards named in honour of the physics Nobel Laureate Paul Dirac. * Dirac Medal (ICTP), awarded by the Abdus Salam International Centre for Theoretical Physics, Trieste * Dirac Medal (IOP), awar ...

of the

Institute of Physics The Institute of Physics (IOP) is a UK-based not-for-profit learned society and professional body that works to advance physics education, physics research, research and applied physics, application. It was founded in 1874 and has a worldwide ...

(UK) in 2000, was awarded the

Lars Onsager Prize The Lars Onsager Prize is a prize in theoretical statistical physics awarded annually by the American Physical Society. Prize recipients receive a medal, certificate, and $10,000. It was established in 1993 by Drs. Russell and Marian Donnelly in m ...

by the APS in 2004, the

Boltzmann Medal The Boltzmann Medal (or Boltzmann Award) is a prize awarded to physicists that obtain new results concerning statistical mechanics; it is named after the celebrated physicist Ludwig Boltzmann. The Boltzmann Medal is awarded once every three years ...

IUPAP The International Union of Pure and Applied Physics (IUPAP; ) is an international non-governmental organization whose mission is to assist in the worldwide development of physics, to foster international cooperation in physics, and to help in the ...

in 2010, the

of the

International Centre for Theoretical Physics The Abdus Salam International Centre for Theoretical Physics (ICTP) is a research center for physical and mathematical sciences, located in Trieste, Friuli-Venezia Giulia, Italy. The center operates under a tripartite agreement between the Gov ...

in 2011, and the

Breakthrough Prize in Fundamental Physics The Breakthrough Prize in Fundamental Physics is one of the Breakthrough Prizes, awarded by the Breakthrough Prize Board. Initially named Fundamental Physics Prize, it was founded in July 2012 by Russia-born Israeli entrepreneur, venture capit ...

in 2024. He is most known for his contributions to

conformal field theory A conformal field theory (CFT) is a quantum field theory that is invariant under conformal transformations. In two dimensions, there is an infinite-dimensional algebra of local conformal transformations, and conformal field theories can sometime ...

. The Cardy formula for black hole entropy, the Cardy formula in

percolation theory In statistical physics and mathematics, percolation theory describes the behavior of a network when nodes or links are added. This is a geometric type of phase transition, since at a critical fraction of addition the network of small, disconnected ...

,arXiv:hep-th/9111026v1
and the Cardy conditions in

boundary conformal field theory Boundary or Boundaries may refer to: * Border, in political geography Entertainment * ''Boundaries'' (2016 film), a 2016 Canadian film * ''Boundaries'' (2018 film), a 2018 American-Canadian road trip film * Boundary (cricket), the edge of the pl ...

are named after him.

Selected works

*
Scaling and renormalization in statistical physics
'. Cambridge University Press, 1996 * with

Krzysztof Gawędzki Krzysztof Gawędzki (Polish pronunciation: ; born 2 July 1947 – died 21 January 2022) was a Polish mathematical physicist, a graduate of the University of Warsaw and professor at the École normale supérieure de Lyon (ENS de Lyon). He was pri ...

, Gregory Falkovich:
Non equilibrium statistical mechanics and turbulence
'. London Mathematical Society Lecture notes, Cambridge University Press, 2008 * ''Conformal Invariance and Statistical Mechanics''. in Les Houches Lectures, vol. 49, 1988 * as editor: ''Finite Size Scaling''. Elsevier 1988
Cardy ''Conformal Invariance in Percolation, Self-Avoiding Walks and Related Problems'', 2002

Cardy ''Conformal field theory and statistical mechanics'', Les Houches Lectures 2008

Cardy, Pasquale Calabrese ''Entanglement entropy and conformal field theory'', J. Phys. A, 42, 2009

Cardy ''Entanglement entropy in extended quantum systems'', 2007

References

External links

John Cardy's homepage
Living people British theoretical physicists American physicists Alumni of Downing College, Cambridge Fellows of All Souls College, Oxford Fellows of Downing College, Cambridge Institute for Advanced Study visiting scholars Fellows of the Royal Society 1947 births Recipients of the Boltzmann Medal {{UK-physicist-stub